Yamaha 9.9 4 stroke with maybe 10 hours. Noticed today while running in test tank after oil change that water is seeping around oil plug. Original oil did not look milky. This has to be bad but I am still under warranty. Any ideas of what might be wrong?

My yamaha has 2 plugs, one in the rear and a dip stick holder. Neither are in contact with the water jacket of the engine and they have no internal access to water. Check that the water tubing around the back of the motor is not leaking and that possibly you aren't getting some splash entering the cowling. Both of these locations are pretty level and will retain water that migrates in from elsewhere.